Balance control during an arm raising movement in bipedal stance: which biomechanical factor is controlled?

Abstract

In order to obtain new insight into the control of balance during arm raising movements in bipedal stance, we performed a biomechanical analysis of kinematics and dynamical aspects of arm raising movements by combining experimental work, large-scale models of the body, and techniques simulating human behavior. A comparison between experimental and simulated joint kinematics showed that the minimum torque change model yielded realistic trajectories. We then performed an analysis based on computer simulations. Since keeping the center of pressure (CoP) and the projection of the center of mass (CoM) inside the support area is essential for equilibrium, we modeled an arm raising movement where displacement of one or the other variable is limited. For this optimization model, the effects of adding equilibrium constraints on movement trajectories were investigated. The results show that: (a) the choice of the regulated variable influences the strategy adopted by the system and (b) the system was not able to regulate the CoM for very fast movements without compromising its balance. Consequently, we suggest that the system is able to maintain balance while raising the arm by only controlling the CoP. This may be done mainly by using hip mechanisms and controlling net ankle torque.

Postural Adjustments in Catching: On the Interplay Between Segment Stabilization and Equilibrium Control

“…On the contrary, our results showed large intra-and intersubject variability in COP-displacement at t 0 (see Figure 5) , with backward and forward shifts, as well as no shifts. Other studies have also failed to show a consistent backward movement of the COP before movement onset (De Wolf, Slijper, & Latash, 1998;Nougier, Teasdale, Bard, & Fleury, 1999;Hay & Redon, 2001;Ferry, Martin, Termoz, Cote, & Prince, 2004;Mochizuki, Ivanova, & Garland, 2004). While such variability has rarely been reported in literature on APA in arm raising, it is notable that there is some suggestion from work on catching a falling ball with an outstretched arm that "signals obtained from force plate showed large variability across subjects" (Shiratori & Latash, 2001, p. 1251.…”

Postural control following a self-initiated reaching task in type 2 diabetic patients and age-matched controls

“…Otherwise the dynamic of the movement seemed to be similar. Ferry et al [29] reported that the accelerations of the body segments are related to the COP displacements. Therefore, in our study, since no significant difference was found in the horizontal acceleration during the completion of the movement, we believe that the task was performed at the same velocity for both groups.…”

Active Control of Bias for the Control of Posture and Movement

“…A5), the kinematic variables being constrained by boundary conditions. This criterion was originally proposed for movement production (Guigon et al 2007b;Harris and Wolpert 1998;Nelson 1983) and was also used for trajectory formation during postural control (Ferry et al 2004;Martin et al 2006;Menegaldo et al 2003). One study (Newman et al 1996) has shown that the two power-law scaling regimes that are typical of physiological sway movements (Collins and De Luca 1993) actually emerge with this same criterion.…”